1. Field of the Invention
The invention relates broadly to a hydraulic braking system, and more specifically to a motorized dumping vehicle having a load-carrying pan tipped by power-operated means and a braking system for gradual stops.
2. Description of the Related Art.
Concrete construction and other work requiring on-the-job transport of heavy materials from one location to another has brought about the development of a variety of relatively small, load-carrying vehicles capable of moving small but often very heavy loads of material on the job site. For example, a frequent need is to load a quantity of concrete at a first location, transport such concrete to a second location and then dump the contents for spreading and screeding operations at the second location. In concrete work such vehicles are often referred to as a "concrete buggy". They may also be referred to as a dump truck or power-driven wheelbarrow. Some of such vehicles are of the walk-behind type while others are of the step or seat-riding type. The load which is carried by a container, called a "skip", "hopper", "pan", or "dump box", is conventionally raised and lowered by a hydraulic piston as in U.S. Pat. Nos. 2,424,670 or 2,427,132. A front pair of single or dual wheels is conventionally driven by a differential and transmission as in U.S. Pat. No. 2,427,132. In the three-wheel-type vehicle, a single or dual wheel supports the rear of the vehicle and is adapted for rotating around a vertical axis for the purpose of steering the vehicle, sometimes with use of a steering mechanism as in U.S. Pat. No. 2,427,132. The conventional way of braking the vehicle is by use of mechanical brakes as illustrated in U.S. Pat. Nos. 2,427,132 and 2,530,574.
My prior U.S. Pat. No. 4,645,264, discloses a motorized dumping vehicle for concrete. In particular, the three-wheel-type dumping vehicle therein disclosed includes a hydraulic drive system for the front wheels with means in the hydraulic system enabling the front wheels to act as brakes and also with means whereby the hydraulic fluid can be cooled within a reservoir which acts both as a structural frame member and as a uniquely-arranged heat sink in which the concrete or other relatively-cool material being transported is used to absorb heat from the hydraulic fluid. This dumping vehicle also includes an improved hydraulic system enabling both the dump box as well as the front wheels to be hydraulically operated and with a minimum requirement of horsepower in the gasoline engine used as the prime source of power for the vehicle.
The art continues to seek improvements. In particular, it is desirable that a braking system bring a dumping vehicle to a gradual stop. If a dumping vehicle stops suddenly or if the braking system locks the wheels of a vehicle, the vehicle is likely to flip or roll, particularly when it is carrying a load. Also, a sudden stop can cause the contents in the pan to spill. Furthermore, a dumping vehicle is likely to slide, particularly when traveling downhill, if the wheels lock during braking.
The present invention seeks to improve upon the dumping vehicle described in the aforementioned U.S. Pat. No. 4,645,264 by providing it with a braking system for gradual stops, thereby reducing the possibility of tipping or rolling because of locked wheels or a sudden stop. Other objects of the present invention will become apparent as the description proceeds.